In general, due to improved dissolving power and capability of dissolved easily in water, an amide-based organic solvent can be subjected to water rinsing, and hence has desired properties as a solvent or a detergent. It can be used as a resist peeling agent or a specific solvent for a hardly-soluble resin such as polyimide and polyamide.
Further, in recent years, since a halogen-based solvent may bring about environment pollution such as ozone layer depletion and has strong toxicity, and NMP or the like has genotoxicity, an amide-based organic solvent can be used in place of these solvents.
Conventional methods for producing this amide-based compound has problems that the production cost thereof is high due to the use of expensive materials as a starting material, the yield is low or the like, and an efficient production method has been desired.
Patent Document 1 (JP-A-S49-66623) discloses a method for the synthesis of β-alkoxy-N,N-dialkylpropionamide as an intermediate in the method for producing a N,N-dialkylpropionamide of an α,β-olefin-based unsaturated monocarboxlic acid which is used as a polymerizable monomer.
This method for the synthesis of a β-alkoxy-N,N-dialkylpropionamide is a method in which a β-alkoxypropionic acid alkyl ester and a dialkylamine are reacted to be amidated in the presence of a polyol having two adjacent hydroxyl groups.
In this method, not only a long period time (20 to 40 hours) is required for the reaction, but also the process becomes complicated due to the need of a neutralization-separation treatment during the reaction process. Accordingly, this method is difficult to be implemented on the industrial scale.
Patent Document 2 discloses a method in which a dialkylacryalamide and an aliphatic monovalent alcohol having 1 to 4 carbon atoms are reacted. According to this method, synthesis can be performed under moderate conditions. However, a dialkylacrylamide is produced through 3 to 4 steps as stated in JP-A-H10-279545. Further, since a dialkylacrylamide itself is expensive, producing a β-alkoxy-N,N-dialkylpropionamide by this method leads to an increase in cost.
Further, a method is known in which dimethylamine is reacted with an alkoxypropionyl chloride, as disclosed in Patent Document 3. For example, reacting dimethylamine with 3-ethoxy-propionylchloride in the presence of a diethyl ether solvent, 3-ethoxy-N,N-dimethylpropionamide can be synthesized.
However, due to expensive raw materials, this method cannot be said as an efficient production method, and hence, is hard to be implemented on the industrial scale.
Further, Patent Document 4 discloses a method in which a β-alkoxypropionic acid alkyl ester is once produced from an acrylic ester, and then a dialkylamine is added, whereby a β-alkoxy-N,N-dialkylpropionamide is produced. In this method, when a β-alkoxy-N,N-dialkylpropionamide is produced from a β-alkoxypropionic acid alkyl ester, a basic catalyst and a polyol are used in combination. The method disclosed in Patent Document 4 suffers a poor yield although a shorter reaction time is needed as compared with the method disclosed in Patent Document 1.
In all of these conventional methods, an amidation reaction is conducted undividedly. When a β-methoxypropionamide is synthesized from methyl β-methoxy propionate by amidation, for example, dimethylamine remains unreacted and methanol formed as a byproduct coexist. Since dimethylamine and methanol are subjected to azeotropy, it is impossible to separate them completely, resulting in an industrial disadvantage.